That’s according to Queanbeyan Fire Rescue station officer Gary Dick who was one of 23 firefighters from Queanbeyan and the ACT called to the Cassidy Street fire at about 3.30pm on Sunday afternoon.

It took firefighters 10 minutes to bring the fire under control and another 35 minutes to extinguish it completely, by which time there was little that could be done to save the property.

“The construction of the building meant that the smallest fire inside would more than likely have built up…and all the heat and smoke generated would have been contained in the unit,” station officer Dick said.

“It may not have been noticeable [from the outside] until it reached a flashover at which point it would have become explosive.

“It was a particularly hot fire that was well fuelled and fairly aggressive.”

The unit complex was evacuated for a short time during the blaze. Fire crews were at one stage concerned for the wellbeing of a neighbouring resident who could not initially be located.

“There was concern for a resident in an upstairs apartment as we were not sure if the occupant was at home at the time,” station officer Dick said.

“[Firefighters] wearing breathing apparatus subsequently gained entry to the upstairs unit and conducted a search where they were able to confirm the unit was empty.”

No one was injured in the blaze and the complex did not sustain structural damage.

The cause of the fire remains undetermined although Queanbeyan Police said they are not treating it as suspicious.